Desenvolvimento de metodologia para determinação simultanea, por CLAE das vitaminas B1, B2, B6, acido nicotinico e nicotinamida em alimentos enriquecidos

AUTOR(ES)
DATA DE PUBLICAÇÃO

1993

RESUMO

The control of enrichment levels in foods is difficult mainly due to the lack of appropriate analytical methodology. A new method for the simultaneous determination of nicotinamide, nicotinic acid, ribotlavin, thiamin and pyridoxine in enriched Brazilian foods by high performance liquid chromatography (HPLC) was developed and evaluated. The new method was employed to determine the vitamin B group in a survey of fifty products, such as cornflour, milk, coconut and sandwich biscuits, cereal flour, lacteous flours, com flakes, macaroni, flavored milk, whole and skim milk powder, acidified milk powder, steritized whole milk, flavored diet drinks and flavored mix for milk-based diet drink. In addition to the simultaneous determination of four vitamins (Bl, B2, B6 and two diferent forms of PP), the advantages of the method developed are: simplicity and improvement in the extraction and cleaning procedures, no use of toxic reagents, use of the UV detector instead of the fluorescent detector, elimination of derivatization reactions and speed in comparison with the official methods. The multivitamin extraction with sulfuric acid in an ultrasonic wave vibrator proved effective. The methanol solution provided partial purification of the extract and prevented precipitation on the analytical column. Neverthless, a gradient elution was necessary in order to get good resolution of the compounds. As the amounts of vitamins in enriched foods are normally greater than usual, the detection can be made using a UV detector. Quantitative data were obtained using calibration curves constructed by plotting peak area versus concentration. Quantification limits of the method and recoveries, in average enrichment levels, were 0.04 μg/ml and 102% for vitamin B1, 0.03 μg/ml and 96% for B2, 0.08 μg/ml and 106% for B6, 0.10 μg/ml and 105% for nicotinamide and 0.03 μg/ml and 81% for nicotinic acid, respectively. Repeated.injections showed a relative standard deviation lower than 5% for vitamin B1, B2 and nicotinamide, 10% for vitamin B6 and 13% for nicotinic acid, respectively. In some of the products analized the vitamin levels agreed with those printed on the package. Although some slight quantitative variations were found within biscuits, one sample had levels of ribot1avin 35% lower than the value stated on the package. Of five different com cereal brands, only one had the declared vitamin content, the others were 30% lower. No B-group vitamins were detected in one brand of enriched macaroni, except for the nicotinic acid naturally present in the t1om. On the other hand, one t1avored milk drink exhibited vitamins levels 200% higher than the amounts stated on the label and one milk drink mix had thiamin, ribot1avin and nicotinamide levels 3 to 5 times greater than stated. These results suggest an absence of control of the amount of vitamins in enriched foods.

ASSUNTO(S)

cromatografia liquida de alta eficiencia vitamina b - complexo alimentos enriquecidos vitaminas - analise

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